This paper attempts to examine the relationship between changes and volatility of China's RMB exchange rates and its agricultural export. A model is constructed to analyze the effect of RMB exchange rate movements on agricultural exports facing two constraints including China's particular exchange rate system and TBT / SPS in agricultural trade. The model reveals that the net trade effect of RMB exchange rate movements relies on the comparison of exchange rate level change (appreciation or depreciation) effect and exchange rate risk effect. Taking China’s agricultural exports to Japan as a case, this paper makes an empirical examination. A GARCH (1, 1) model is specified to measure the exchange rate volatility and ADL regression with structural break dummy variables is estimated based on the results of unit root test with structural break. The results show RMB depreciation against yen will promote export growth while appreciation hinder export, and exchange rate volatility positively stimulates agricultural exports to Japan. However, the effect of exchange rate volatility on the export is much smaller than that of exchange rate level, which leads to a negative net effect to the export. The policy implications among the empirical results are also discussed.